As smokeless tobacco (ST) usage increases in the United States, it becomes increasingly important to determine both its short and long term effects on oral health. Currently there is especially limited information describing the associations between ST use and dental caries and periodontal diseases, despite many public assertions of positive associations. This 18-month study is specifically designed to answer the questions: (1) What is the relation between the use of ST and periodontal diseases, including gingival recession, gingivitis and periodontitis, and (2) dental caries? Participants will be enrolled from two groups of men at the U.S. Naval Recruit Training Command, Great Lakes, Illinois; male recruits (R), aged 17-23 years, and nonrecruits (NR), aged 18-50, a group which includes officers and enlisted personnel. Two study designs will be used, one for each group. A case-control design will be employed for the NR. Based on previous diagnosis of periodontitis, NR of similar ages with and without this condition will be selected and matched. Histories of exposure to ST among the disease and nondisease groups will be compared. Since pre-existing diagnostic information is not available for the R a cross-sectional design weighted for prevalence of use will be employed. After a brief screening form, R will be selected based on ST exposure status. Oral health status of users and nonusers will be compared. In both designs, the data collection methods include a self-administered questionnaire to collect information regarding product use, ddmographic information, and variables such as smoking history which may influence oral health status. For R, clinical examinations will be conducted by dentists experienced in the use of specified dental epidemiologic indices including measures of corpnal and root caries, plaqu7e, calculus, gingival recession, gingivitis, attrition and abrasion. Leukoplakia and potentiol precancerous conditions will be noted and referrals made. For the NR, the oral health status will be oltained from dental records. Each study design will require separate analysis. Multivariate analysis will be applied to control for potential confounding factors. Results will provide the firmest data yet collected on the association between ST use and oral conditions.